Ammonia is applied to soils as a nitrogen fertilizer and to silage as a non-protein nitrogen source. The ammonia used for these purposes is usually stored in compressed form as a liquid at ambient temperature. Because of its vapor pressure, liquid ammonia at ambient storage is generally under a pressure of about 80 to about 200 psig. Conventionally, ammonia is applied to soils by injection through a series of so-called knives, which are pulled through the soil at a depth of about 6 to 15 inches. The ammonia is supplied from a pressure tank through a metering valve and discharged behind the tip of each knife. The pressure of the ammonia is released partly at the metering valve and partly at the knife end. Since the expansion of compressed ammonia occurs instantaneously, an intimate mixture of vapor and droplets form at the point of expansion.
Ammonia is also used to treat forage in the preparation of silage to provide a non-protein nitrogen source suitable for animal consumption. In this case, ammonia is applied directly to freshly cut forage material such as corn or sorghum.
Ammonia in the form of an aqueous solution has been applied to anaerobically fermentable plant material for silage production to provide feed for ruminant animals, the applied ammonia being converted to nitrogen compounds providing non-protein nitrogen (NPN) which is consumable by ruminant animals, as taught, for example, in U.S. Pat. No. 3,753,723, incorporated herein by reference. In field applications such as in soil fertilization and trench silage production, this method has serious disadvantages due to the necessity of carrying a separate water supply along with the ammonia and other field equipment. A more economical and simpler method of application of ammonia to soils and silage is described in U.S. Pat. Nos. 3,978,681 and 4,069,029, each incorporated herein by reference, which disclose a method in which the pressure of the compressed, liquid ammonia is released prior to application in an expansion chamber which separates the gas from the liquid. Both phases are then applied to the soil or silage separately, thereby allowing a more uniform flow and a safer non-pressure application. An additional advantage of this method is that it permits, in the case of soils, the application of ammonia with a conventional disc harrow or cultivator instead of a special knife applicator. Since the cold liquid and gaseous ammonia produced by this process does not flash or sputter at substantially atmospheric pressure as easily as when pressurized liquid ammonia is applied to the soil directly in the prior art process, the cold ammonia can be applied to the top of the soil or at much shallower depths in combination with the field cultivator so that the cold ammonia thus applied is covered immediately by the soil turned over by the field cultivator. Thus a separate trip over the field to apply ammonia is eliminated. This results in fuel, labor, and machinery wear savings. Also eliminated is the need for knife maintenance and replacement costs.
The expansion chamber of U.S. Pat. No. 3,978,681 is designed to utilize gravity for the separation of the gaseous and liquid ammonia. In essence, the ammonia is introduced in the center of the chamber through an inlet pipe from which the liquid phase falls to the bottom and the gas rises to the top. Each phase is discharged through pipes in the bottom and the top, respectively. To improve the separation, each discharge exit is shielded with a baffle plate to avoid entrainment of liquid with the gas phase, and vice versa.
The liquid phase is then passed through a distribution device which divides the flow into several streams of equal portions to be applied to the soil through individual hoses. Gaseous ammonia is similarly applied through another set of hoses.
The shortcoming of this baffled device is mainly in the rather inefficient phase separation in the expansion chamber. In applications of ammonia to soils, relatively large quantities of ammonia have to be expanded and separated into the liquid and gas phases. Rates of up to 8,000 pounds per hour are not uncommon. To separate ammonia at such high rates requires a very large expansion chamber. Thus, a device which would avoid the need for a large and heavy piece of equipment is highly desirable and useful. Since the expansion chamber may be moved from one piece of field equipment to another by the farmer or other end user, it is very important that the size and weight of the expansion chamber be such that it can readily be moved by hand by a few and preferably one individual.
The device of U.S. Pat. No. 4,069,029 overcame some of the aforementioned inefficient separation problems by a process wherein the liquid and gaseous ammonia of reduced pressure from an inlet conduit from a pressure tank is added tangentially into a cylindrical chamber at velocities exceeding 5,000 feet per minute. This creates a fast circular motion in the chamber which forces the liquid to the wall where it descends in a spiral pattern to the bottom outlet. The gas, being lighter than the liquid, is forced to the center and upward to the outlet at the top. To increase the capacity, a second stage containing a mist eliminator may be added.
However, even with the improved efficiency of the equipment of this latter patent, the equipment is often of sufficiently large size and of significant complexity to build that it presents considerable cost to manufacture. This is particularly true due to the need for a separate mist eliminator on this equipment. When the size of this prior art equipment is significantly reduced, the ammonia capacity is so severely reduced that a large field cultivator may require many different expansion chambers attached across the width of the cultivator in order to apply the ammonia at the desired rate. Additionally, the gas outlet tube coming from the top of the chamber often has problems with crimping when flexible tubing is utilized resulting in excessive wear or damage and uneven distribution in the gaseous ammonia lines. To avoid this crimping problem, extra cost is involved in changing the direction of the gaseous ammonia from its initial upward direction to a downward direction so that it can be applied to the soil, to forage, etc.